add
RTS_PREFIX = $(FPTOOLS_TOP)/common-rts/
(Harmless unless compiling for the new RTS).
HAPPY_PREFIX = $(FPTOOLS_TOP)/happy/src/
GREENCARD_PREFIX = $(FPTOOLS_TOP)/green-card/src/
+RTS_PREFIX = $(FPTOOLS_TOP)/common-rts/
+
UNLIT_PREFIX = $(FPTOOLS_TOP)/ghc/utils/unlit/
UGEN_PREFIX = $(FPTOOLS_TOP)/ghc/utils/ugen/
STAT2RESID_PREFIX = $(FPTOOLS_TOP)/ghc/utils/stat2resid/